Alice
I'm a bit worried that the Earth is freezing in the middle!
Rob
Don't worry, Alice! In this case, because of the incredibly high pressure in the core, the
freezing point of iron is actually about 6000 degrees! And the iron has been cooling down
and crystallizing for a billion years – and at a rate of just half a millimetre every year.
Alice
Ah well, yes, that sounds like slow progress.
Rob
Certainly. Now moving on, we should also talk about the fact that it's the liquid iron outer
core that generates magnetic fields – and it's thanks to these magnetic fields that life on
Earth is possible. Let's hear more about this.
Bragg_talks_to_Arwen_Deuss,_seismologist_at_Utrecht_University_Deuss'>Melvyn Bragg talks to Arwen Deuss, seismologist at Utrecht University
Deuss: Well, the magnetic field is very important because it protects us against cosmic
radiation so that's one really...
Bragg: How does it do that?
Deuss: It just creates a shield, which will just deflect the cosmic rays from the Sun to
actually reach us at the surface. So it protects us.
Bragg: So it goes up there…
Deuss: Yeah, so you would see that the radiation kind of goes into the Earth and not
actually reach us.
Alice
So there's a magnetic field round the Earth that protects us from the Sun's cosmic rays. I'd
like a magnetic field round me. It could be my superpower – like in X Men!
Rob
Calm down, Magneto. Now the magnetosphere is the area around the Earth in which the
Earth's magnetic field is felt. It protects us from the Sun's radiation and the flow of particles,
which would otherwise strip away – or remove – the Earth's atmosphere.
Alice
Right, I see. And what does 'radiation' mean?
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